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Mixing in gravity currents

Published online by Cambridge University Press:  08 October 2013

A. T. Fragoso ,
M. D. Patterson  and
J. S. Wettlaufer
A. T. Fragoso
Affiliation:
Yale University, New Haven, CT 06520-8109, USA
M. D. Patterson
Affiliation:
University of Bristol, University Walk, Bristol BS8 1TR, UK
J. S. Wettlaufer
Affiliation:
Yale University, New Haven, CT 06520-8109, USA Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
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Abstract

We study entrainment in lock-release gravity currents using highly spatially resolved optical transmission experiments and quantitative analysis of the available potential energy of the flow. The principal results provide a resolution to the debate regarding the mechanism and degree of mixing in the head of a gravity current during the slumping phase. The nature of the complex internal mixing structure changes as a bore propagates from the tail to the head of the current during the slumping phase and overtakes its leading edge. We use quantitative methods to identify the connection between dynamics and entrainment and show that its manifestation as examined using different methodologies is the cause of previous contradictory experimental findings. Therefore, we conclude that the two main perspectives previously considered at odds are in accord.

JFM classification

Geophysical and Geological Flows: Gravity currents Mixing: Turbulent mixing
Type
Rapids
Information
Journal of Fluid Mechanics , Volume 734 , 10 November 2013 , R2
Copyright
©2013 Cambridge University Press 

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References

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Fragoso et al. supplementary movie

Experiment 1, raw image: Water level 10 cm, Aspect Ratio = 0.5, Fractional Depth = 1, Reduced Gravity = 12

Download Fragoso et al. supplementary movie(Video)
Video 1.7 MB

Fragoso et al. supplementary movie

Experiment 2, processed image: Water level 30 cm, Aspect Ratio = 1.5, Fractional Depth = 1, Reduced Gravity = 12

Download Fragoso et al. supplementary movie(Video)
Video 3.6 MB

Fragoso et al. supplementary movie

Experiment 3, processed image: Water level 25 cm, Aspect Ratio = 2.5, Fractional Depth = 1, Reduced Gravity = 12

Download Fragoso et al. supplementary movie(Video)
Video 2.4 MB

Fragoso et al. supplementary movie

Experiment 4, processed image: Water level 15 cm, Aspect Ratio = 0.5, Fractional Depth = 0.67, Reduced Gravity = 12

Download Fragoso et al. supplementary movie(Video)
Video 2.7 MB

Fragoso et al. supplementary movie

Experiment 5, processed image: Water level 30 cm, Aspect Ratio = 0.5, Fractional Depth = 0.33, Reduced Gravity = 12

Download Fragoso et al. supplementary movie(Video)
Video 1.9 MB

Fragoso et al. supplementary movie

Experiment 6, processed image: Water level 20 cm, Aspect Ratio = 1, Fractional Depth = 1, Reduced Gravity = 12

Download Fragoso et al. supplementary movie(Video)
Video 3.1 MB

Fragoso et al. supplementary movie

Experiment 7, processed image: Water level 20 cm, Aspect Ratio = 1, Fractional Depth = 1, Reduced Gravity = 24

Download Fragoso et al. supplementary movie(Video)
Video 2.2 MB

Fragoso et al. supplementary movie

Experiment 8, processed image : Water level 20 cm, Aspect Ratio = 1, Fractional Depth = 1, Reduced Gravity = 36

Download Fragoso et al. supplementary movie(Video)
Video 1.6 MB